Bottom up top down cordless shade

ABSTRACT

A cordless bottom up top down window covering is disclosed. The window covering includes a headrail, an intermediate rail, a bottom rail, at least one lift cord extending through each of the headrail, intermediate rail and bottom rail, at least one post or unidirectional wheel located in the intermediate rail, and a single lifting mechanism operatively connected to the at least one lift cord. The lift cords are engaged with either the post or unidirectional wheel.

BACKGROUND OF THE INVENTION

Bottom up top down (herein after “BUTD”) window coverings are oftenemployed in situations where it is desired to selectively cover/uncoverdifferent portions of a window (i.e.—top portions and bottom portions).The use of standard window coverings, whether typical Venetian blinds,cellular shades or the like, only allows for the covering of a windowfrom the top of the window down. Therefore, the covering of the windowusing such standard window coverings always insures that either theentire window is uncovered, or at least a top portion of the window iscovered. BUTD window coverings are made so that they can be raised andlowered from the top as well as from the bottom. Thus, a user canselectively cover or uncover either the top portion or bottom portion orsome intermediate portion of a window.

Prior art BUTD window coverings include a headrail, an intermediaterail, and a bottom rails. A window covering material is often disposedbetween the intermediate rail and the bottom rail, and in certain BUTDwindow coverings, between the headrail and the intermediate rail. Priorart BTUD window coverings typically utilize one set of lift cords forthe bottom rail, and another set of lift cords for the intermediaterail. These cords are operated independently of each other, andtypically locked in place with cord locks. Thus, movement of theintermediate rail or the bottom rail requires the use of differentmechanisms that each must be manipulated to engage or disengage the cordlock to hold or release the given rail. This setup typically causesconfusion as to which lock operate. Similarly, where the mechanisms forengaging or disengaging the cord locks are cords or chains, theabundance of the cords or chains creates a situation in which tanglingis likely.

Therefore, there exists a need for a cordless or chainless BUTD windowcovering.

SUMMARY OF THE INVENTION

The present invention relates to window coverings and liftingmechanisms, more particularly, to bottom up top down window coveringsincorporating the use of a spring motor.

A first aspect of the present invention is a bottom up top down windowcovering. The window covering according to this embodiment includes aheadrail, an intermediate rail, a bottom rail, at least one lift cordextending through each of the headrail, intermediate rail and bottomrail, means for balancing and tensioning the at least one lift cord, andmeans for retracting the at least on lift cord. The means for balancingand tensioning the at least one lift cord may be posts or unidirectionalwheels among other means. The means for retracting the at least one liftcord may be a spring motor or any other suitable means as is known inthe art.

Another embodiment of the present invention is another bottom up topdown window covering. The window covering according to this aspectincludes a headrail, an intermediate rail, a bottom rail, at least onelift cord extending through each of the headrail, intermediate rail andbottom rail, at least one post located in said intermediate rail, and atleast one spring motor operatively connected to the at least one liftcord. The at least one lift cord is frictionally engaged with the atleast one post, and the at least one lift cord is capable of beingretracted by the at least one spring motor.

The window covering according to the above embodiment may include a pairof lift cords, a pair of posts and a single spring motor located in thebottom rail for retracting the pair of lift cords. The intermediate railmay be moveable with respect to the headrail and the bottom rail. Thefrictional engagement of the lift cords with the posts is achieved bywrapping each lift cord around a different post. The spring motoraccording to this embodiment may include a main body, a pair of cordspools rotatably mounted on the main body, each of the cord spoolsconnected to one of the pair of cords, a drum rotatably mounted on acentral portion of the main body, the drum in rotatable engagement withthe pair of cord spools, and a pair of coil springs connected to thedrum, the coil springs each being biased to rotate the drum whichrotates the cord spools to wind the each of the cords onto one of thespools. The window covering may also include a locking mechanism toreleasably secure the cords in position. Actuation of the lockingmechanism allows movement of the bottom rail.

An upward force applied to the bottom rail of the window coveringaccording to this embodiment may allow the intermediate rail to movedownward. The intermediate rail may also be positioned by applying aforce directly thereto. In certain configurations, the window coveringmay additionally include a centrally located pulley in the intermediaterail. The at least one lift cord may be wrapped around the pulley.Finally, the window covering may include shade material having two ends.One end of the shade material may be connected to the intermediate railand the other end may be connected to the bottom rail.

Another embodiment of the present invention is another bottom up topdown window covering. The window covering according to this embodimentincludes a headrail, an intermediate rail, a bottom rail, at least onelift cord extending through each of the headrail, intermediate rail andbottom rail, at least one unidirectional wheel located in saidintermediate rail, and at least one spring motor operatively connectedto the at least one lift cord. The at least one lift cord is engagedwith the at least one unidirectional wheel, and the at least one liftcord is capable of being retracted by the at least one spring motor.

Yet another embodiment of the present invention is another bottom up topdown window covering. The window covering according to this embodimentincludes a headrail, an intermediate rail including a pulley, a bottomrail including at least one spring motor, and a pair of lift cords. Eachlift cord is wrapped around the pulley. Each lift cord has an endconnected to the headrail and an end operatively connected to the atleast one spring motor, where the lift cords are capable of beingretracted by the spring motor.

Another aspect of the present invention is a method of positioning abottom up top down window covering. The method according to this aspectincludes providing a window shade including a head rail, an intermediaterail, a bottom rail, at least one lift cord extending through each ofthe headrail, intermediate rail and bottom rail, means for balancing andtensioning the at least one lift cord, and at least one spring motoroperatively connected to the at least one lift cord, wherein the atleast one lift cord is capable of being retracted by the spring motor.The method also includes moving the bottom rail upwardly or downwardly,wherein movement of the bottom rail downwardly includes pulling the atleast one lift cord away from the spring motor, and movement of thebottom rail upwardly includes lifting the bottom rail while the at leastone lift cord is retracted by the spring motor. Finally, the method alsoincludes the step of moving the intermediate rail.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the subject matter of the presentinvention and the various advantages thereof can be realized byreference to the following detailed description in which reference ismade to the accompanying drawings in which:

FIG. 1 is a perspective view of a bottom up top down window coveringaccording to one embodiment of the present invention positioned suchthat substantially all of a window may be covered.

FIG. 2 is a perspective view of the bottom up top down window coveringaccording to FIG. 1 positioned such that a top portion of a window maybe uncovered while a lower portion is covered.

FIG. 3 is a front view of the bottom up top down window coveringaccording to FIG. 1 positioned such that substantially all of a windowmay be uncovered.

FIG. 4 is a perspective view of the bottom up top down window coveringaccording to FIG. 2, showing internal elements in phantom.

FIG. 5 is a side cross-sectional view of the bottom up top down windowcovering according to FIG. 2.

FIG. 6A is a front cross-sectional view of the intermediate rail of thebottom up top down window covering according to FIG. 2.

FIG. 6B is a top cross-sectional view of the intermediate rail of thebottom up top down window covering according to FIG. 2.

FIG. 6C is a front cross-sectional view of the intermediate rail of abottom up top down window covering according to an embodiment of thepresent invention having unidirectional wheels.

FIG. 6D is a front cross-sectional view of the intermediate rail of abottom up top down window covering according to an embodiment of thepresent invention having unidirectional wheels and a pulley.

FIG. 6E is a front cross-sectional view of the intermediate rail of abottom up top down window covering according to an embodiment of thepresent invention only having a pair of posts.

FIG. 6F is a front cross-sectional view of the intermediate rail of abottom up top down window covering according to an embodiment of thepresent invention only having a pulley.

FIG. 7 is an exploded perspective view of a lifting mechanism for usewith the bottom up top down window covering according to the presentinvention.

FIG. 8 is a cross-sectional view of the lifting mechanism according toFIG. 7.

FIG. 9 is a perspective view of a portion of a locking device used inthe lifting mechanism according to FIG. 7.

FIG. 10 is a cross-sectional view of the lifting mechanism according toFIG. 7 showing the cooperation of the lifting mechanism with the liftcords.

FIG. 11 is a partial cross-sectional view of the lifting mechanismaccording to FIG. 7.

DETAILED DESCRIPTION

In describing the preferred embodiments of the subject matterillustrated and to be described with respect to the drawings, specificterminology will be used for the sake of clarity. However, the inventionis not intended to be limited to any specific terms used herein, and itis to be understood that each specific term includes all technicalequivalents which operate in a similar manner to accomplish a similarpurpose.

Referring to the drawings, wherein like reference numerals representlike elements, there is shown in the Figures, in accordance withembodiments of the present invention, a bottom up top down cordlesswindow covering designated generally by reference numeral 10. As shownin FIGS. 1-3, window covering 10 includes a head rail 12, anintermediate rail 14, and a bottom rail 16. A shade material 18 isdisposed between intermediate rail 14 and bottom rail 16. In theembodiment shown in FIGS. 1-3, shade material 18 is a cellular materialof a generally opaque nature. However, it is contemplated that manydifferent types of shade material can be utilized. For example, certainembodiments might utilize pleated shades or Venetian blinds. Similarly,it is also contemplated that in certain embodiments an additionalportion of shade material may be connected at some point between headrail 12 and intermediate rail 14. As is best shown in FIG. 2, a pair oflift cords 20 and 22 are fixed in headrail 12, pass through intermediaterail 14, and are secured in bottom rail 16. This will be discussedfurther below. Finally, a lifting mechanism 24 is associated with bottomrail 16.

FIGS. 1-3 show three of the many different positions that windowcovering 10 can be arranged in. FIG. 1 shows window covering 10 in aposition in which it may substantially cover an entire window. FIG. 2illustrates a position in which a top portion of a window may beuncovered, while a lower portion is covered. FIG. 3 depicts windowcovering 10 in a fully open position, allowing for substantially all ofa window to be uncovered. It is contemplated that window covering 10 maybe positioned in various other manners that selectively cover or uncovertop or bottom portions of a window. For example, window covering 10 canbe positioned so that both a top portion and a bottom portion of awindow may be uncovered, while a central portion is covered.

According to one preferred embodiment, FIGS. 4 and 5 illustrate thecooperation of lift cords 20 and 22 with the other elements of windowcovering 10. As shown in the figure, lift cords 20 and 22 are attachedto headrail 12. It is contemplated that lift cords 20 and 22 may befixed to headrail 12 in any fashion known in the art. For example, liftcords 20 and 22 may be tied off to a portion of headrail 12. Lift cords20 and 22 exit headrail 12 through holes located therein. The cords thenextend through a closed top of intermediate rail 14, through similarholes to those of head rail 12 and wrap around posts 26 and 28, as wellas pulley 30. Finally, after exiting intermediate rail 14 through itsopen bottom, lift cords 20 and 22 run between shade material 18 (bestshown in FIG. 5) and extend into bottom rail 16, where they areoperatively connected to lifting mechanism 24. This operative connectionwill be discussed further below. It is noted that the routing of liftcords 20 and 22 through headrail 12, intermediate rail 14 and bottomrail 16 may include fixing the cord ends to one of the rails, or simplyallowing the cords to run through the rails. For example, as mentionedabove, lift cords 20 and 22 can each be fixed to headrail 12.Additionally, eyelets 23 and cord guides 25 may be employed at theentrances and exits of the rails, respectively. For example,intermediate rail 14 may include eyelets 23 where lift cords 20 and 22enter intermediate rail 14, and cord guides 25 where lift cords 20 and22 exit intermediate rail 14.

As is best shown in FIGS. 6A 6B, posts 26 and 28 are rounded bodies thatextend from the front of intermediate rail 14 to the rear. Lift cords 20and 22 are wrapped around posts 26 and 28 so as to allow the posts, andhence intermediate rail 14, to slide along the cords. However, in apreferred embodiment, posts 26 and 28 are designed to create africtional force upon the lift cords. This frictional force is derivedfrom the cooperation of lift cords 20 and 22 with posts 26 and 28respectively, with the hanging weight of bottom rail 16 impartingtension to the cords. In operation, this frictional force preventsintermediate rail 14 from moving under its own weight. Therefore, themovement and positioning of intermediate rail 14 may only be achieved intwo different ways.

In a first way, a force may be directly applied to intermediate rail 14by a user. Such force may be sufficient to overcome the frictional forceprovided by the cooperation of the posts and the lift cords. It iscontemplated that the force applied directly to intermediate rail 14 maybe applied in such a fashion so as to allow the raising or lowering ofthe rail. Additionally, in a second way, intermediate rail 14 can belowered by lifting up the bottom rail 16, and therefore removing thehanging weight force, and thus lessening the tension on the cords. Thislifting of bottom rail 16 dramatically decreases the frictional forcebetween the posts and the lift cords, and allows intermediate rail 14 todescend along lift cords 20 and 22 under its own weight. Thus, absent aforce applied directly to intermediate rail 14 or the lifting of bottomrail 16, intermediate rail 14 is designed to remain in place. It iscontemplated that posts 26 and 28 can be constructed in a manner or of aspecific material that increases the aforementioned frictional force.For example, posts 26 and 28 can be constructed of a rubber materialhaving a relatively high coefficient of friction.

As is also shown in FIGS. 6A and 6B, intermediate rail 14 of thisembodiment includes a pulley 30, in addition to posts 26 and 28. Pulley30 is substantially circular and further includes tracks 32 and 34 forreceiving lift cords 20 and 22 respectively, and circular channel 36 forreceiving a circular axel 38 coupled to intermediate rail 14. In theembodiment shown in FIGS. 6A and 6B, pulley 30 is freely rotatable andis situated in the center of intermediate rail 14. Lift cord 20 comingdownward from headrail 12 is thread under post 26, around track 32, andback over post 26. Similarly, lift cord 22 coming downward from headrail12 is thread under post 28, around track 34, and back over poster 28.This configuration allows for the aforementioned creation of africtional force by posts 26 and 28, while pulley 30 ensures thatintermediate rail 14 remains in a substantially parallel orientation,with respect to headrail 12 and bottom rail 16, during the raisingand/or lowering of intermediate rail 14. In operation, pulley 30 rotateswith the raising and lowering of intermediate rail 14. Pulley 30requires lift cords 20 and 22 to move into and out of intermediate rail14 at the same rate, giving even lift or lowering on both sides of therail. The raising and/or lowering of intermediate rail 14 may beperformed in a similar fashion to that disclosed above.

FIG. 6C depicts another embodiment for keeping intermediate rail 14 inplace. This embodiment is an intermediate rail 14 having unidirectionalwheels or ratchets 40. Unidirectional wheel 40 may be any rotationaldevice that allows rotation in a single rotational direction. Forexample, as shown in FIG. 6C, wheel 40 includes angled fingers 42 thatinteract with catch 44. The uniform angled configuration of fingers 42allow wheel 40 to freely rotate in a first direction, but catch 44prevents rotation in a second and opposite direction. Intermediate rail14, as shown in FIG. 6C, includes two wheels 40, one that freely rotatesin a clockwise direction, and one that freely rotates in acounterclockwise direction. These two wheels 40 in turn allow forintermediate rail 14 to freely move in an upwards direction. However,wheels 40 prevent intermediate rail 14 from freely moving in a downwarddirection by providing a frictional force similar to that created byposts 26 and 28. Similarly, the downward motion of intermediate rail 14is achieved like that disclosed above in the discussion relating toposts 26 and 28. Application of direct downward force upon intermediaterail 14 or lifting of bottom rail 16 will once again allow intermediaterail 14 to move in a downwardly fashion.

It is contemplated that different embodiments may include differentcombinations of the elements previously disclosed. For example, whilethe embodiment shown in FIGS. 6A and 6B depict an intermediate railincluding a combination of posts and a pulley, other embodiments mayinclude a combination of unidirectional wheels or ratchets and a pulley,like that shown in FIG. 6D. In another embodiment, like that of FIG. 6C,a window covering 10 may be provided that merely includes a pair ofposts 26 and 28. This is shown in FIG. 6E. It is also contemplated thata pulley can be utilized that provides for both a frictional force to becreated and the uniform raising and lowering of the intermediate rail.For example, as shown in FIG. 6F, a pulley could be utilized that ratherthan being capable of rotating, is fixed in a position. This may allowfor the raising and lowering of the intermediate rail in a similarfashion to that disclosed above in the discussion relating to the postsor unidirectional wheels. In other words, the fixed pulley would actmore like the aforementioned posts. Additionally, a pulley could beutilized that is similar to the aforementioned unidirectional wheels.This may allow for the easy raising of the intermediate rail, whileproviding a more difficult manner of lowering. Finally, it is noted thatthe various elements located in intermediate rail 14 can be situated inmany different ways. For example, the locations of posts, wheels, andpulleys can be at any portion of intermediate rail 14.

FIG. 7 shows an exploded view of a suitable lifting mechanism 24 for usewith the present invention. Lifting mechanism 24, as shown in thefigures, is a spring motor in accordance with that disclosed and claimedin commonly owned U.S. patent application Ser. No. 10/452,170, thedisclosure of which is hereby incorporated by reference herein. However,lifting mechanism 24 as shown in FIG. 7 is only a single example of asuitable lifting mechanism. For example, other lift mechanisms aredisclosed in U.S. Pat. Nos. 5,904,198; 6,012,506; 6,024,154; 6,047,759;6,056,036; 6,079,471; 6,095,222; 6,129,131; 6,129,181; 6,149,094;6,289,965; 6,293,329; 6,325,131; 6,330,899; 6,491,084; 6,508,293; and6,536,503 and U.S. Patent Publication Nos. 2002/0011315; 2002/0088562;2002/0157796; and 2003/0070767, the disclosures of which are all herebyincorporated by reference herein. It is contemplated that any liftingmechanism, as is known in the art, may be utilized in conjunction withthe present invention.

The lifting mechanism depicted in various views in FIGS. 7-11 is aspring motor assembly 112 which comprises a main body 124 and a topplate 125, a pair of cord spools 126, 128 rotatably mounted on the mainbody 124 and disposed between the main body and top plate 125. Cordspools 126 and 128 are generally cylindrical in shape, and each of thespools includes a bore 127 and 129. Cord spools 126 and 128 may bemounted on a pair of spindles or posts 130 and 132, and each of thespindles or posts is adapted to receive one of the spools 126 or 128through their respective bores, 127 and 129 to allow the spools tofreely rotate. It will be understood that the spools can be mounted tomain body 124 by other suitable means. Each cord spool 126 and 128 isconnected to one lift cord 20 or 22, as will be described in more detailbelow.

Spring motor assembly 112 further comprises a drum 134 rotatably mountedon a central portion of main body 124. Drum 134, like spools 126 and128, may include a bore 135, as best seen in FIG. 7. The central portionof main body 124 may further include a spindle 133 adapted to receivebore 135 of drum 134 to allow the drum to freely rotate on spindle 133.

According to one or more embodiments, drum 134 is in rotatableengagement with the pair of cord spools 126 and 128. Drum 134 ispreferably in rotatable engagement with cord spools 126 and 128 viaengagement surfaces such as gears associated with each of the spools andthe drum. For example, spool 126 may include a gear 136, and spool 128may include a gear 138, both of which engage with a gear 144 associatedwith drum 134. As shown in FIG. 7, spool gears 136 and 138 are integralwith spools 126 and 128, and drum spool gear 144 is a separate componentfrom drum 134. This design facilitates assembly and disassembly of thelifting mechanism, however, it is understood that the variousembodiments are not limited to this design. Thus, for example, spoolgears 136 and 138 may be separate components that can be mounted ontheir respective spools 126 and 128, and drum gear 144 can be integralwith drum 134. Of course, other variants are possible. All of the gearsmay be integral with their respective spools and drum, or all of thegears may be separate components from their respective spools and drum.

Mounting of drum gear 144 on drum 134 may be accomplished by providingcomplementary mating surfaces on the drum and the gear. For example,drum 134, may include a male hexagonal surface 140, as seen in FIG. 7,and gear 144 may include a female hexagonal opening 142 adapted to bereceived on the male hexagonal surface. Alternatively, gear 144 mayinclude a male hexagonal surface while the drum may include a hexagonalrecess (not shown) adapted to receive the male surface on gear 144.Other mating surfaces for mounting gear 144 on drum 134 may be utilized.

According to one or more embodiments, spring motor assembly 112 furtherincludes a pair of coil springs 146 and 148 disposed loosely aroundspindles 130 and 132, but without storage spools. Preferably, each coilspring 146 and 148 is located coaxially with each of cord spool 126 and128. Thus, in certain embodiments, cord spools 126 and 128 arerespectively disposed above the coil springs 146 and 148. Coil springs146 and 148 are connected, on one end, to drum 134. When bottom rail 16is in a raised position, a major portion of the coil spring is wrappedaround its respective spindle. When the bottom rail 16 is pulled down aportion of each spring is transferred onto drum 134. Springs 146 and 148are attached to center drum 134 and configured in a way that when centerdrum 134 is rotated while bottom rail 16 is being lowered, both ofsprings 146 and 148 resist (or act opposite) such rotation. When windowcovering 10 is raised again by lifting bottom rail 16 and releasing alocking device (described below), coil springs 146 and 148 are biased torotate drum 134, and the drum rotates cord spools 126 and 128 to windcords 20 and 22, onto their respective spools. Thus, coil springs 146and 148, do not directly drive cord spools 126 and 128, and they are notin contact with the cord spools. In other words, while the windowcovering is being raised, coil springs 146 and 148 are biased to rotatea member separate from the cord spools, and this member in turn rotatesthe cord spools. The coil springs are selected and biased withsufficient force so that cord spools 126 and 128 are driven withsufficient force by drum 134 to take up their respective cords 20 and 22while the blind is being raised.

Preferably, coil springs 146 and 148 are releasably attached to drum134. Drum 34 further includes spring engagement surfaces 150 and 152(not shown), which are in the form of arcuate slots formed in drum 134.Preferably the drum is hollow, and each spring 146 and 148 has apartially narrowed end section 156 and 158. Springs 146 and 148preferably have the same thickness and the width “w” of the spring issubstantially the same over the length of the spring. In preferredembodiments, both ends of each spring 146 and 148 have the same width.Partially narrowed end sections 156 and 158 provide an engagementsurface with spring engagement surfaces 150 and 152 of the drum. Thus,each spring 146 and 148 is engaged with drum 134 by inserting narrowedend sections 156 and 158 in one of the arcuate slots in drum 134 andthen turning each end section 156 and 158 approximately 90 degrees tolock spring 146 and 148 to the drum. Of course, other means can be usedto engage springs 146 and 148 and drum 134. For example, tabs,complementary spindles and openings and other means can be utilized toengage achieve the same result.

According to one or more embodiments, spring motor assembly 112 furtherincludes a release device or locking mechanism 154 to releasably lockthe cords in place and prevent the cords from winding onto the spoolswhen bottom rail 16 is in a lowered position on a window. Preferablylocking mechanism 154 is associated with main body 124. Main body 124includes a pair of cord slots 160 and 162 (shown in FIG. 8) that arewide enough to allow cords 20 and 22 to travel therethrough withoutbinding when the cords are being released from or wound on theirrespective spools 126 and 128. As used herein, the term slot includesopen passages or grooves and closed passages or holes. Locking mechanism154 further comprises at least a first, and preferably a pair of lockingarms 164 and 166, which are attached to locking handle 174, in slidingengagement with the a portion of main body 124.

As best shown in FIG. 9, locking arms 164 and 166 each have a channel170 and 172 through the arm for allowing cords 20 and 22 to traveltherethrough freely when the cord is being released from or wound on thespool. As used herein, channel is not limited to an open passage throughthe locking arm, and it can include a closed passage through the lockingarm. As shown in FIG. 7, locking mechanism 154 includes a biasingmechanism including at least one spring 173 for moving locking armchannel 170 and 172 out of alignment with their respective cord slots160 and 162 to releasably lock cords 20 and 22 in position. Preferably,the biasing mechanism includes a pair of springs 173. Thus, in therelaxed state locking mechanism 154 is in the biased and locked positionand cord 20 is pinched by the out of alignment locking arm channel 170and slot 160. Similarly, in the locked position, cord 22 is pinched bythe out of alignment locking arm channel 172 and cord slot 162. Whencompressive force is applied to locking arms 164 and 166 through handle174, cord channel 170 in locking arm 164 is brought into alignment withcord slot 160 of main body 124. Similarly, cord channel 172 in lockingarm 166 is brought into alignment with cord slot 162 in main body 124.Conveniently, locking arms 164 and 166 are part of a locking handle thatcan be compressed by gripping spring motor assembly 112 in the hand andsqueezing locking handle 174 in the direction shown by arrows 175 inFIG. 10. It will be appreciated that the size of the slots and channelswill depend on the size of the cord used to fabricate the windowcovering, and a skilled artisan can select the proper size slot andchannel.

In use, the cords 20, 22, are taken up on spools 126 and 128 when thecords are released from the pinched configuration by squeezing lockinghandle 174 and lifting up on bottom rail 16. Coil springs 146 and 148rotate drum 134 and cause cord spools 126 and 128 to take up the cordsas the bottom rail is being lifted. In one or more embodiments, the drumprovides substantially uniform rotation for each spool 126 and 128,resulting in even lift of the window covering. Thus, when hand-operatedlocking mechanism 154 is released and it is desired to move bottom rail16 upward, the tendency of springs 146 and 148 to return to theirnatural state causes center drum 124 to rotate in a direction thatcauses springs 146 and 148 to return to positions loosely surroundingposts 130 and 132. This causes center gear 144 to rotate, which in turncauses cord gears 136 and 138 to rotate, thus taking in lift cord.

Referring to FIGS. 7 and 11, spring motor assembly 112 further includesa pair of plugs 176 and 178 having respective openings 177 and 179therethrough adapted to guide cords 20 and 22 from a horizontalorientation in bottom rail 16 to a substantially vertical orientation toguide cords 20 and 22 up through the shade material 18, intermediaterail 14, and headrail 12. Plugs 176 and 178 are preferably press fit inbottom rail 16, however, they may also be screw fit or adhesivelyattached to bottom rail 16.

Thus, according to one or more embodiments of the present invention, alifting mechanism is provided in which two springs are taken up by acentral drum, which acts as a single output drum, providing a compact,powerful unit that provides even lift of the window covering. The twoseparate springs are positioned directly below the cord spools but notdirectly connected to the cord spools, which maximizes the use of spaceof the bottom rail. Thus, the lifting mechanism can replace a portion ofthe bottom rail and be an integral part of the rail. The lockingmechanism can be concealed from view by positioning the lockingmechanism to face the rear of the bottom rail. The lifting mechanism iscompact in design, in part due to the fact that the locking mechanismincludes two relatively thin arms that are inserted into the main bodyof the lifting mechanism, with cord channels or openings being locatedin those arms. Once again, it is contemplated that the aforementionedspring motor assembly 112 is only one example of a lifting mechanism 24for use with bottom up top down window covering 10.

Intermediate rail 14 is situated such that the movement of bottom rail16 in an upwards direction will, at a certain point, similarly moveintermediate rail 14 in an upwards direction. Therefore, the operationof lifting mechanism 24 and the lifting of bottom rail 16 will allow forthe winding of lift cords 20 and 22 and the upward movement ofintermediate rail 14 upon contact of bottom rail 16. This operation ofbottom rail 16 allows for the selective covering and uncovering of awindow as in other window coverings that are known in the art. Asdiscussed above, positioning of the remainder of window covering 10 maybe accomplished by positioning intermediate rail 14. To moveintermediate rail in a downward fashion, either a direct force may beapplied by a user, or a slight lifting of the bottom rail may be done toremove the aforementioned frictional force. To move intermediate rail 14in an upward fashion, either a direct upward force may be applied by auser, or lifting mechanism 24 may be actuated in conjunction with thelifting of bottom rail 16 until contact is made between the two rails.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. A bottom up top down window covering comprising: a headrail; anintermediate rail; a bottom rail; at least one lift cord extendingthrough each of said headrail, intermediate rail and bottom rail; meansfor balancing and tensioning said at least one lift cord; and means forretracting said at least one lift cord.
 2. The bottom up top down windowcovering according to claim 1, wherein said intermediate rail ismoveable with respect to said headrail and said bottom rail.
 3. Thebottom up top down window covering according to claim 1, wherein saidmeans for balancing and tensioning said at least one lift cord is atleast one post and said at least one lift cord is engaged with the atleast one post.
 4. The bottom up top down window covering according toclaim 1, wherein said means for balancing and tensioning said at leastone lift cord is at least one unidirectional wheel and said at least onelift cord is engaged with the at least one unidirectional wheel.
 5. Thebottom up top down window covering according to claims 3 or 4, whereinsaid means for balancing and tensioning said at least one lift cordfurther includes at least one pulley and said at least one lift cord isengaged with the at least one pulley.
 6. The bottom up top down windowcovering according to claim 5, wherein said means for retracting said atleast one lift cord is a spring motor.
 7. The bottom up top down windowcovering according to claim 6, wherein said intermediate rail ismoveable with respect to said headrail and said bottom rail.
 8. Thebottom up top down window covering according to claim 7, wherein saidwindow covering includes a pair of lift cords, a single spring motorlocated in said bottom rail for retracting said pair of lift cords, alocking mechanism to releasably secure said pair of lift cords inposition, and shade material connected between said intermediate railand said bottom rail, wherein an upward force on said bottom rail allowssaid intermediate rail to move downward and wherein said intermediaterail can be positioned by applying a force directly thereto.
 9. Thebottom up top down window covering according to claim 1, wherein saidmeans for balancing and tensioning said at least one lift cord is atleast one pulley and said at least one lift cord is engaged with the atleast one pulley.
 10. A bottom up top down window covering comprising: aheadrail; an intermediate rail; a bottom rail; at least one lift cordextending through each of said headrail, intermediate rail and bottomrail; at least one post located in said intermediate rail, said at leastone lift cord frictionally engaged with said at least one post; and atleast one spring motor operatively connected to said at least one liftcord, wherein said at least one lift cord is capable of being retractedby said at least one spring motor.
 11. The bottom up top down windowcovering according to claim 10, wherein said intermediate rail ismoveable with respect to said headrail and said bottom rail.
 12. Thebottom up top down window covering according to claim 11, wherein saidat least one lift cord is wrapped around said at least one post.
 13. Thebottom up top down window covering according to claim 12, wherein saidwindow covering includes a pair of lift cords, two posts, each lift cordwrapped around a different post, and a single spring motor located insaid bottom rail for retracting said pair of lift cords.
 14. The bottomup top down window covering according to claim 13, further comprising apulley centrally located in said intermediate rail, said pair of liftcords engaged with the pulley.
 15. The bottom up top down windowcovering according to claim 14, wherein said spring motor includes amain body; a pair of cord spools rotatably mounted on the main body,each of the cord spools connected to one of the pair of cords; a drumrotatably mounted on a central portion of the main body, the drum inrotatable engagement with the pair of cord spools; and a pair of coilsprings connected to the drum, the coil springs each being biased torotate the drum which rotates the cord spools to wind the each of thecords onto one of the spools.
 16. The bottom up top down window coveringaccording to claim 15, further comprising a locking mechanism toreleasably secure the cords in position.
 17. The bottom up top downwindow covering according to claim 16, wherein actuation of said lockingmechanism allows movement of said bottom rail, an upward force on saidbottom rail allows said intermediate rail to move downward, and whereinsaid intermediate rail can be positioned by applying a force directlythereto.
 18. The bottom up top down window covering according to claim17, further comprising shade material connected to said intermediaterail and said bottom rail.
 19. A method of positioning a bottom up topdown window covering comprising: providing a window shade including ahead rail, an intermediate rail, a bottom rail, at least one lift cordextending through each of said headrail, intermediate rail and bottomrail, means for balancing and tensioning said at least one lift cord,and at least one spring motor operatively connected to said at least onelift cord, wherein said at least one lift cord is capable of beingretracted by the spring motor; moving said bottom rail upwardly ordownwardly, wherein movement of said bottom rail downwardly includespulling said at least one lift cord away from said spring motor, andmovement of said bottom rail upwardly includes lifting said bottom railwhile said at least one lift cord is retracted by said spring motor; andmoving said intermediate rail.
 20. The method according to claim 19,wherein said moving of said intermediate rail includes lifting up saidbottom rail in order to lower said intermediate rail or applying a forcedirectly thereto.